Comparison of Hemodynamic Performance, Three-Dimensional Flow Fields, and Turbulence Levels for Three Different Heart Valves at Three Different Hemodynamic Conditions.

Abstract

The hemodynamic performance of different prosthetic heart valves is difficult to compare among studies due to a variety of test conditions and experimental techniques. Existing studies are typically limited to one family of valves (biological or mechanical) and testing conditions of 5l/min and often lack sufficient spatial resolution. To address these limitations, a pulse duplicator with a multi-view imaging system (Tomo-PIV) was employed to investigate the three-dimensional flow field in the aortic root of three different valves: a tri-leaflet mechanical heart valve (TRIFLO, Novostia), a bi-leaflet mechanical heart valve (On-X, Artivion), and a biological heart valve (Perimount, Edwards Lifesciences). The valves were tested at low (3 l/min), normal (5 l/min), and elevated (7 l/min) cardiac output <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mo>(</mo> <mi>C</mi> <mi>O</mi> <mo>)</mo></mrow> </math> under hypotensive (40/60mmHg), normotensive (80/120mmHg), and moderate hypertensive (105/170mmHg) pressure conditions, respectively. Compared to the Perimount, peak mean velocity was - 33%, - 24%, - 18% for the TRIFLO and - 32%, - 20%, - 11% for the On-X at low, moderate, and elevated <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>CO</mi></mrow> </math> , respectively. Corresponding peak <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>TKE</mi></mrow> </math> values decreased by - 66%, - 57%, - 44% (TRIFLO) and - 60%, - 50%, - 36% (On-X). At low <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>CO</mi></mrow> </math> , <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>EOA</mi></mrow> </math> was lower for Perimount (1.07cm²) than for TRIFLO (1.47cm²) and On-X (1.52cm²), while it increased for elevated <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>CO</mi></mrow> </math> to 2.75cm² (TRIFLO) and 2.16cm² (Perimount and On-X). For all valves, increasing <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>CO</mi></mrow> </math> led to increased flow velocities, higher <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>E</mi> <mi>O</mi> <mi>A</mi> <mo>,</mo></mrow> </math> and higher levels of turbulence, and the spatial influence of the valve on the flow field in the ascending aorta was extended. <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>TKE</mi></mrow> </math> peaked closer to the STJ than for TRIFLO and Perimount.